diff --git a/lib/errors/OperationStateError.ts b/lib/errors/OperationStateError.ts
index 794464d7..46f5024a 100644
--- a/lib/errors/OperationStateError.ts
+++ b/lib/errors/OperationStateError.ts
@@ -22,10 +22,28 @@ export default class OperationStateError extends HiveDriverError {
 
   public response?: TGetOperationStatusResp;
 
+  // SQLSTATE reported by the server for the failed operation (if any)
+  public sqlState?: string;
+
   constructor(errorCode: OperationStateErrorCode, response?: TGetOperationStatusResp) {
     super(response?.displayMessage ?? errorMessages[errorCode]);
 
     this.errorCode = errorCode;
     this.response = response;
+
+    // Only the top-level field describes the failed operation: `status` is
+    // always a successful GetOperationStatus RPC status by the time this is thrown.
+    const sqlState = response?.sqlState;
+    if (sqlState) {
+      // Non-enumerable, matching how the kernel backend attaches `sqlState`
+      // (see `defineErrorMetadata` in lib/kernel/KernelErrorMapping.ts), so the
+      // same error class looks identical regardless of backend.
+      Object.defineProperty(this, 'sqlState', {
+        value: sqlState,
+        writable: true,
+        enumerable: false,
+        configurable: true,
+      });
+    }
   }
 }
diff --git a/tests/e2e/operation_error_codes.test.ts b/tests/e2e/operation_error_codes.test.ts
new file mode 100644
index 00000000..d1a2eb72
--- /dev/null
+++ b/tests/e2e/operation_error_codes.test.ts
@@ -0,0 +1,59 @@
+import { expect, AssertionError } from 'chai';
+import { DBSQLClient } from '../../lib';
+import IDBSQLSession from '../../lib/contracts/IDBSQLSession';
+import OperationStateError, { OperationStateErrorCode } from '../../lib/errors/OperationStateError';
+
+import config from './utils/config';
+
+// Regression for https://github.com/databricks/databricks-sql-nodejs/issues/33 —
+// errors thrown for failed operations should carry a machine-readable code
+// (SQLSTATE) at the top level, not only a message buried in `response`.
+describe('Operation error codes', () => {
+  let client: DBSQLClient;
+  let session: IDBSQLSession;
+
+  before(async () => {
+    client = new DBSQLClient();
+    const connection = await client.connect({
+      host: config.host,
+      path: config.path,
+      token: config.token,
+    });
+    session = await connection.openSession({
+      initialCatalog: config.catalog,
+      initialSchema: config.schema,
+    });
+  });
+
+  after(async () => {
+    await session?.close();
+    await client?.close();
+  });
+
+  async function expectOperationStateError(query: string) {
+    try {
+      const operation = await session.executeStatement(query);
+      await operation.fetchAll();
+      expect.fail('It should throw an error');
+    } catch (error) {
+      if (error instanceof AssertionError) {
+        throw error;
+      }
+      expect(error).to.be.instanceOf(OperationStateError);
+      return error as OperationStateError & { sqlState?: string };
+    }
+    throw new Error('unreachable');
+  }
+
+  it('should expose server SQLSTATE on OperationStateError for runtime failures', async () => {
+    const error = await expectOperationStateError("SELECT raise_error('boom')");
+
+    expect(error.errorCode).to.be.eq(OperationStateErrorCode.Error);
+
+    const wireSqlState = error.response?.sqlState;
+    expect(wireSqlState, 'server should send a SQLSTATE on the wire').to.be.a('string');
+    expect(wireSqlState).to.have.length(5);
+
+    expect(error.sqlState).to.be.eq(wireSqlState);
+  });
+});
diff --git a/tests/unit/errors/OperationStateError.test.ts b/tests/unit/errors/OperationStateError.test.ts
new file mode 100644
index 00000000..ac38c371
--- /dev/null
+++ b/tests/unit/errors/OperationStateError.test.ts
@@ -0,0 +1,53 @@
+import { expect } from 'chai';
+import OperationStateError, { OperationStateErrorCode } from '../../../lib/errors/OperationStateError';
+import { mapKernelErrorToJsError } from '../../../lib/kernel/KernelErrorMapping';
+import { TOperationState, TStatusCode } from '../../../thrift/TCLIService_types';
+
+describe('OperationStateError', () => {
+  it('should expose response.sqlState at top level', () => {
+    const error = new OperationStateError(OperationStateErrorCode.Error, {
+      status: { statusCode: TStatusCode.SUCCESS_STATUS, sqlState: '00000' },
+      operationState: TOperationState.ERROR_STATE,
+      sqlState: '22012',
+      displayMessage: 'Division by zero',
+    }) as OperationStateError & { sqlState?: string };
+
+    expect(error.errorCode).to.be.eq(OperationStateErrorCode.Error);
+    expect(error.message).to.be.eq('Division by zero');
+    expect(error.sqlState).to.be.eq('22012');
+  });
+
+  it('should not take sqlState from the RPC status', () => {
+    const error = new OperationStateError(OperationStateErrorCode.Error, {
+      status: { statusCode: TStatusCode.SUCCESS_STATUS, sqlState: '00000' },
+      operationState: TOperationState.ERROR_STATE,
+    });
+
+    expect(Object.prototype.hasOwnProperty.call(error, 'sqlState')).to.be.false;
+  });
+
+  it('should attach sqlState with the same descriptor as the kernel backend', () => {
+    const thriftError = new OperationStateError(OperationStateErrorCode.Error, {
+      status: { statusCode: TStatusCode.SUCCESS_STATUS },
+      operationState: TOperationState.ERROR_STATE,
+      sqlState: '22012',
+    });
+    const kernelError = mapKernelErrorToJsError({ code: 'SqlError', message: 'x', sqlstate: '22012' });
+
+    expect(kernelError).to.be.instanceOf(OperationStateError);
+    expect(Object.getOwnPropertyDescriptor(thriftError, 'sqlState')).to.deep.eq(
+      Object.getOwnPropertyDescriptor(kernelError, 'sqlState'),
+    );
+    expect(Object.keys(thriftError)).to.not.include('sqlState');
+    expect(JSON.parse(JSON.stringify(thriftError))).to.not.have.property('sqlState');
+  });
+
+  it('should not define sqlState when the server reports none', () => {
+    const error = new OperationStateError(OperationStateErrorCode.Error, {
+      status: { statusCode: TStatusCode.SUCCESS_STATUS },
+      operationState: TOperationState.ERROR_STATE,
+    });
+
+    expect(Object.prototype.hasOwnProperty.call(error, 'sqlState')).to.be.false;
+  });
+});